Electric contact device



3, A. WELLMAN I 2,435,484

ELECTRIC CONTACT DEVICE Filed Dec. '7, 1946 Invehbor: 1.; i5 Albert Welhman,

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2,435,484 ELECTRIC CONTACT DEVICE Albert Wellman, Schenectady, N. Y., assignor to General Electric Com New York pany a corporation of Application December 7, 1946, Serial No. 714,698

4 Claims.. (01. 200-4) My invention relates to electric contact devices and more particularly to electromagnetic relay contacts having a single movable contact element providing both normally open and normally.

closed contacts. v

It is a general object of my invention to pro-v vide a new and improved electromagnetic relay contact element of the above type which is durable, reliable, and positive in operation as well as inexpensive in manufacture and assembly.

It is a more particular object of my invention having a single unitary spring contact element providing both normally open and normally closed contacts.w

Briefly,'-my invention in one form comprises a planar movable contact element of electric conducting material having a bridging contact arm and a pair ofresilient auxiliary contact, arms extendihg outwardly from opposite sides of the bridging arm at opposite ends thereof. actuating member movable perpendicularly to the plane of the contact element is connected to the center of the contact element to move the bridging arm transverselyas a bridging contact, while fixed abutments are provided to engage the auxiliary arms intermediate their ends during the actuating movement. The abutments act as fulcrums for the resilient auxiliary arms, so that during movement of the actuating member in one direction the contact carrying free ends oi! the auxiliary arms move in the opposite direction.

The novel features which are characteristic of my invention will be set forth more particularly in the appended claims. For a clearer understanding of the various features, objects and advantages of the invention, reference should first be had to the accompanying drawing in which Fig. 1 is a plan view of one end 01 a relay embodying my invention; Fig. 2 is a cross-sectional view taken along the line 2-2 of Fig. 1; Fig. 3 is a plan view of the opposite end of the relay; Fig. 4 is a cutout view showing the contactor, contactor tips, pivots, and mounting member; and Fig. 5 is an exploded perspective view of the entire relay.

Referring now to the drawing, I have shown an electromagnetic relay comprising 9, coil I, a core 2, a movable plunger 3. and a movable contact element 4 connected to the plunger by an actuating pin 5. The energizingcoil I is wound upon a hollow insulating spool 8 and is removably positionedwithin a cup-shaped housing 1 formed integrally with the core 2 and o! magnetizable material. An upper cup-shaped coil housing 8 of magnetizable material fits over the coil in to provide a new and improved contact device telescoping relation with the lower housing 1.

The upper housing 8'15 provided with a reentrant tubular portion 9 within which the plunger 3 is slidably positioned. Pressed into the tubular portion 8 is a thin cup-shaped liner l0 oia nonmagnetic material, such as brass. The liner Ill provides a permanent magnetic -air gap in the flux path. the function of which will be made clear hereinafter.

'I'he movable plunger 3 and the core 2 are formed of magnetizable material and are position'ed within the central aperture in the coil spool 6. The core extends-into the spool from the bottom of the cup-shaped housing 1 and the upper end of the plunger is reduced in diameter in order that it will fit slidably into the brass liner Ill. The liner Ill thus serves as a bearing for the plunger 3, as well as providing a magnetic air gap for the flux path. Since the liner l0 constitutes a necessary air gap in the magnetic circuit, it is formed in such a manner as to present a large area for the passage of flux between the top of the housing 8 and the plunger 3. This construction minimizes the reluctance of the brass liner Ill. In order to minimize the holding force resulting from the flux leakage between the lower edge of the tubular portion 9 and the head of the plunger 3, the air gap between them is made several times as large as the gap across the brass liner l0, as illustrated in Fig. 2.

A thin spring washer l I is placed between the face of the upper flange of the spool 6 and the top of the housing 8, as shown at Fig. 2. to minimize jarring oi the coil i under highirequency vibration, such as might result from use on aircraft or the like.

The actuating pin 5 is formed oi! non-magnetic material and is slidably mounted within a central longitudinal bore in the core 2. The upper end of the pin 5 is reduced in diameter, as at 5a, and flts into a recess in the movable plunger 3, as shown in Fig. 2. The lower end of the pin 5 is reduced in diameter, as at 521, and fits into a knob l2 having at its upper end a. peripheral shoulder Ho. The knob 12 serves to transmit downward actuating movement 01' the plunger 3 and pin 5 to the contact member 4.

The movable contact element 4 is formed of resilient electric conducting material and includes a central bridging contact arm i3 and a pair of like outwardly extending contact arms I. Th arms 14 extend from opposite sides of the bridging contact arm I! at opposite ends thereof, as shown in Figs. 3 and 5. In the form of the invention shown, the contact element 4 is substantially of S- or Z-shape, the arms I4 being arcuate and extending in opposite directions on opposite sides of the diametrical central arm I3.

'IWvo pairs of contacts I5 and I6 are fixed to an insulating base I1 and arranged for engagement with the ends of the movable bridging arm I3 and the free ends of the resilient arms I4, respectively. The insulating base is provided also with a pair of diametrically disposed slotted shoulders I8 arranged slidably to engage opposite ends of the bridging arm I 3, thereby to guide the contact member 4 in its movement. Formed upon the base I1 I provide also a pair of fixed abutments or pivots I9 positioned to engage the resilient contact arms I4 intermediate their ends. The insulating base I! is mounted in a cylindrical housing 20 of insulating material, within which is mounted also the coil and core structure, as shown at Fig. 2. Leads for the coil I are brought out through apertures 2| in the base of the cupshaped housing I and aligned apertures 22 in the insulating base I I. Where the leads pass through the housing I they are provided with insulating bushings 23.

The contact member 4 is provided with a central aperture and the base II is provided with an aligned central recess, both designed to slidably accommodate the knob I 2. The peripheral shoulder I2a of the knob I2 thus bears against the contact element 4 at its center and moves substantially perpendicularly to it upon movement of the actuating pin 5.

Within the central recess in the base I! is seated a helical compression spring 21. The upper end of the spring 24 fits over the knob I2 where the knob passes through the aperture in the contact element 4. so that the contact element is biased upwardly by the spring and away from the base II. In this normal position the fixed contacts I5 are spaced from the ends of the bridging arm I3. while the fixed contacts I6, being raised above the contacts I5, are in engagement with the free ends of the contact arms ii.

In operation. when coil I is energized magnetic flux is established in a path including the core 2, the cup-shaped housing I. the upper housing I, the brass liner I0, and the plunger 3. The plunger 3 and actuating pin 5 move the contact member 4 downward against the bias of the spring 24 and r the resilient contact arms ii. The initial downward movement of the contact element 4 causes a slight sliding movement between the free ends of the arms I4 and the fixed contacts I8. This wiping is advantageous in that it breaks any welds which may have formed between the normally closed contacts I4 and I8. Continuation of downward movement of the pin 5 causes pivoting oi the resilient arms I4 upon the abutments I 9, as illustrated in Fig. 4, thus moving the free outer ends of the arms I4 upward and separating the normally closed contacts I4 and I8 substantially simultaneously with the closing of the normally open contacts I5 and I3.

The deflection of the resilient contact arms I 4 causes an upward bias by these arms which acts as a kick-off spring when the downward pressure of the actuating pin is removed. Thus, the resilience of the movable contact member 4 serves to aid in resetting the contact member and provides a force in addition to that of the biasing spring 24 to break any weld which may have formed between the contacts II and the movable bridging arm II.

Settings oi contector gap thickness and air gap are automatically made with the assembly of the relay. After assembly and test the whole unit may be coated with a heavy layer 01' moistureresisting insulating paint to seal 01! the flux path against leakage to surrounding magnetic materials. The base plate I! may be sealed by a sealing compound around its rim, as shown in Fig. 2, to prevent moisture from reaching the contactor tips. The relay is now hermetically sealed without requiring any additional enclosures over the fiux path, and may be mounted on a base of any suitable material by means of a mounting bracket 25. As shown, the bracket 25 is attached to a housing I and is preferably oi non-magnetic material.

While I have described only one preferred embodiment oi my invention by way of illustration, many modifications will occur to those skilled in the art, and I therefore wish to have it understood that I intend in the appended claims to cover all such modifications as fall within the true spirit and scope oi my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an electric contact device, a base having two pairs oi fixed contacts mounted thereon, a planar movable contact member of electric conducting material including a bridging contact arm and a pair of resilient contact arms extending outwardly from opposite sides oi said bridging arm at opposite ends thereof, said bridging arm cooperating with one said pair of fixed contacts, and the free ends of said resilient arms cooperating with the other said pair of fixed contacts, on actuaing member connected to move said bridging arm transversely and in a plane substantially perpendicular to the plane of said contact element, and a pair of fixed abutments mounted upon said base and positioned to engage said resilient contact arms intermediate their ends, said resilient arms pivoting about said abutment when said bridging arm is moved in one direction by said actuating member thereby to move the free ends of said resilient arms in the opposite direction. 2. In an electric contact device. a base having two airs or fixed contacts mounted thereon, a planar movable contact member of resilient electric conducting material including a bridging contact arm and e. pair of auxiliary contact arms extending outwardly from opposite sides of said bridging arm at opposite ends thereof, means for normally positioning said contact element with the free ends of said auxiliary arms in engagement with one said pair of fixed contacts and opposite ends of said bridging arms spaced from the other said pair oi fixed contacts, an actuating member connected to move said bridging arm substantially transversely of the plane of said contact element to bridge said other pair of fixed contacts. and a pair of fixed abutment; mounted upon said base and positioned to engage said auxiliary arms intermediate their ends during the actuating movement, said auxiliary arms pivoting about said abutments thereby to separate the free ends of said auxiliary arms from said one pair of fixed contacts.

3. In an electric contact device, a base of insulating material having two pairs of fixed contacts mounted thereon. a. substantially s-shaped movable contact member f resilient electric conducting material including a central bridging contact arm and a pair of arcuate auxiliary contact arms extending from opposite sides of said central arm at opposite ends thereof, spring means for normally positioning said contact element to maintain the free ends of said auxiliary arms in engagement with one said pair of said fixed contacts and opposite ends of said central arms spaced from the other said pair of fixed contacts, an actuating member movable substantially perpendicular to the plane oi said contact element and arranged to engage said contact element at substantially the center of said central bridging arm, said actuating member being movable substantially perpendicular to the plane of said contact element to move said bridging arm into engagement with said other pair of fixed contacts and a pair of flxed abutments mounted upon said base and positioned to engage said auxiliary arms intermediate their ends, said auxiliary arms pivoting about said abutments during actuating movement thereby to move the free ends of said auxiliary arms out of engagement with said one pair of fixed contacts.

4. An electric control device comprising a cylindrical casing having an axially movable actuating member mounted in one end thereof and a contact compartment at the other end thereof,

(.a circular base of insulating material in said con. 1' tact compartment having two pairs of fixed contacts diametrically mounted thereon, a substantially s-shaped movable contact member of resilient electric conducting material including a diametrical bridging arm and a pair or arcuate auxtion with the other said pair of fixed contacts, an

actuating in interposed between said actuating member and said movable contact element, said actuating pin being movable substantially perpendicular to the plane of said contact element thereby to move said diametrical arm into bridging engagement with said other pair of fixed con. tacts, and a pair of fixed abutments mounted upon said base and positioned to engage said auxiliary arms intermediate their ends, said auxiliary arms pivoting about said abutments in the actuating movement thereby to move the free ends of said auxiliary arms out of engagement with said one pair or fixed contacts.

ALBERT WELLMAN.

REFERENCES CITED The following references are of record in the tile 01' this patent:

UNITED STATES PATENTS Number Name Date Wellman July 3, 1945 

